[RTTY] Frequency Accuracy

[Dick Kriss]

On Aug 16, 2011, at 3:27 AM, KenwoodTS-590 at yahoogroups.com wrote:

> Frequency Accuracy
> Posted by: "Bob Warmke" w6cyx at arrl.net   bobwarmke
> Mon Aug 15, 2011 8:46 pm (PDT
> 
> John,
> W1AW is often not on the exact frequency they claim. Please check on only 
> WWV. They are always right on the "money".
> Bob, W6CYX 
> 

I agree with Bob W6CYX; however, the W1AW RTTY bulletin is where I check my frequency calibration for RTTY.  I have been in touch with the W1AW station manager and he indicates they are  rock solid on frequency in CW mode; however, they have had some frequency offset issues with digital modes. These offset issues with a custom version of the MixW software used by W1AW have been resolved.

On 15-Aug-2011, I ran a test using my Kenwood TS-590S with the SO-3 TCXO and the new version of fldigi-3.21.12 by W1HKJ that now reports and logs the RTTY Mark while in AFSK. As a backup I ask Dick K4JJW to listen and record the W1AW RTTY bulletin using his Icom IC-7700 using MMTTY in FSK mode.

Before conducting the test I calibrated my TS-590S to WWV using the fldigi Frequency Analysis tool and ran into some issues with what may be a defective Kenwood SO-3 TCXO; however, I did manage to get the TS-590S calibrated pretty close to the WWV signals on 5, 10, 15 and 20 MHz. The suspect SO-3 is another discussion topic.

As expected the W1AW RTTY signal was very easy to detect and decode.  I moused on the signal on the waterfall display and accepted the fldigi reported "QSO Freq" (RTTY Mark) and read 14095.020 which I though was close enough for amateur use. W1AW broadcasts in AFSK with an offset such that listeners with rigs in FSK mode should copy the W1AW signal at 14095.  Shortly after the test, I got an email from K4JJW that he copied the W1AW signal at 14095.020 in FSK on his Icom IC-7700 

What is amazing about the the test was getting a Kenwood TS-590S user in AFSK mode on a Mac and Icom IC-7700 user in FSK mode on a PC to AGREE on a RTTY frequency! 

WWV is great for calibration but for quick checks I copy the W1AW RTTY bulletin. 


73 Dick AA5VU